Seamless steel containers

ABSTRACT

A steel beverage or beer can of the seamless type having a unitary body including seamless side walls and an integral bottom with an end double seamed to the top of the side walls. The bottom comprises an outer frustoconical surface extending downwardly and inwardly from the side walls, an annular bead for supporting the can, an inner frustoconical surface extending upwardly and inwardly from the annular supporting bead, and a recessed domed central panel extending inwardly and upwardly along the axis of the can from the second frustoconical surface.

United States Patent Kneusel et al.

' 51 Sept. 26, 1972 [54] SEAMLESS STEEL CONTAINERS [72] Inventors: Raymond B. P. Kneusel, Flourtown, Pa.; Vinson S. Potts, Cherry Hill, NJ.

[73] Assignee: Crown Corp & Seal Company, Inc. [22] Filed: July 22, 1970 [21] Appl. No.: 57,124

[52] US. Cl ..220/66, 220/70, 220/97 R [51] Int. Cl. ..B65d 7/42 [58] Field of Search ..220/70, 66, 67, 97 R; 215/10 [56] References Cited UNITED STATES PATENTS 3,272,383 9/1966 Harvey ..220/66 3,279,640 10/ 1966 Dodson ..220/70 X 3,343,670 9/1967 Stephan ..206/65 C 3,349,956 10/1967 Stephan ..220/97 R 3,355,060 11/1967 Reynolds et al. ..220/54 3,369,694 2/1968 Mauser et a1 ..220/97 R X FOREIGN PATENTS OR APPLICATIONS 272,187 9/1968 Austria ..220/66 Primary Examiner-George E. Lowrance Assistant Examiner-James R. Garrett Attorney-Woodcock, Washburn, Kurtz & Mackiewicz [5 7] ABSTRACT A steel beverage or beer can of the seamless type having a unitary body. including seamless side walls and an integral bottom with an end double seamed to the top of the side walls. The bottom comprises an outer frustoconical surface extending downwardly and inwardly from the side walls, an annular bead for supporting the can, an inner frustoconical surface extending upwardly and inwardly from the annular supporting bead, and a recessed domed central panel extending inwardly and upwardly along the axis of the can from the second frustoconical surface.

6 Claims, 8 Drawing Figures PATENTEUSEPZB I912 3.693.828

SHEET 1 [IF 2 g j Fig. 1 I

PRIOR ART Fig 3 7 RC 1 SEAMLESS STEEL con'mmsas BACKGROUND OF THE INVENTION This invention relates to so-called seamless containers. More particularly, this invention relates to containers comprising a drawn unitary body having seamless side walls and integral bottom and further comprising an end double seamed to the top of the seamless side walls.

Containers of this type as contrasted with conventional side-seamed containers have particular utility in the beverage or beer can industry for esthetic reasons. Presently, the conventional, side-seamed can having two doubled seamed ends dominates the beverage or beer industry, but the appearance of the container leaves much to be desired. In particular, the side seam of the conventional can interferes with the printing and illustrations on the can. Although substantial efforts have been made in minimizing the prominence of the side seam and thereby minimizing the interference or discontinuity in the labeling and illustrations, the side seam has remained a substantial eye sore on even the most attractive beverage or beer cans.

In an effort to rid the beverage or beer container of the unsightly side seam, substantial efforts have been made over the years to develop a container comprising a body having a seamless side wall and an integral bottom. In general, these efforts fall in one of two categories depending upon the metal used, aluminum or steel.

Aluminum is considered desirable for the fabrication of seamless cans because of the ductility of this metal.

Because of this ductility, aluminum may be cupped, redrawn, and wall ironed with substantial ease into al most any configuration desired. For example, US. Pat. No. 3,349,956 Stephan and U.S. Pat. No. 3,343,670 Stephan disclose different configurations in the bottom panel of a seamless can which has been drawn from an aluminum blank. The configuration shown in FIG. 3 of these patents is particularly intricate and serves as an example of aluminums high degree of ductility.

Although aluminum has been used commercially for seamless containers, it does have certain drawbacks which have resulted in the limited acceptance of aluminum by the beer and beverage can industry. Undoubtedly, the most significant drawback is the cost of aluminum. Since seamless cans are used as disposable cans in this industry and must therefore represent a small fraction of the product selling price, it is particularly important that the seamless can be very inexpensive.

Another drawback of aluminum is the low resistance to the internal pressure produced by the contents within the can. As a rule of thumb, the beverage or beer can must be capable of withstanding an internal pressure of 100 PSI (pounds per square inch). If the resistance is sufficiently low to permit eversion of the bottom at a lesser internal pressure, the can is unsuitable for carbonated beverages such as beer and soft drinks. In some instances where increased pressure resistance has been provided, the stability or the ability of the can to stand upright has decreased. In other instances, the bottom of the can has been made thicker requiring more costly aluminum.

In view of the foregoing difficulties associated with seamless containers comprising aluminum, substantial efforts have been made to utilize steel or coated steel which is the material most commonly utilized in the conventional side-seamed can. Yet, in spite of the lower cost of steel as compared with aluminum, the seamless steel can has not been manufactured or sold on any extensive commercial basis.

One reason that the seamless steel can has not been accepted is due to difficulties in coating the interior at the bottom. The proper drawing angle for sheet steel dictates the configuration of the can bottom to some degree. The resulting configuration of the bottom has been difficult to coat. Although coating is not particularly critical in an aluminum can, this is not thecase with the steel can. In fact, the steel can which is not properly coated is unusable for purposes of beer or beverages. Of course, the configuration of the bottom must also provide the necessary resistance to pressures of PSI. In order to achieve such a resistance in prior art cans, a very heavy gauge of steel must be utilized as a blank. This of course requires more steel which is expensive and/or more wall ironing to reduce the side wall thickness to a thickness substantially less than the heavy gauge bottom. As a result, the prior art drawn steel containers have not achieved significant commercial acceptance by the beverage and beer can industry.

SUMMARY OF THE INVENTION It is a general object of this invention to provide a commercially acceptable seamless steel container for the beverage and beer can industry.

It is one specific object of this invention to provide an improved seamless steel container permitting uniform and adequate coating.

It is a further specific object of this invention to provide a highly pressure resistant improved seamless steel container.

It is a still further specific object of this invention to provide such an improved seamless steel container having a broad base of support to prevent the container from tipping over.

It is yet another specific object of this invention to provide an improved seamless steel container comprising a minimum of steel.

In accordance with these and other objects, a steel container capable of withstanding internal pressure of 100 PSI comprises a unitary body having seamless substantially cylindrical side walls and a bottom integrally formed with the side walls at the lower extremity thereof. The bottom includes an outer substantially frustoconical surface extending downwardly and inwardly from said side walls toward the axis of said container, an annular bead extending from the first frustoconical surface providing an annular supporting surface for the container, an inner substantially frustoeonical surface extending upwardly and inwardly from the annular bead toward the axis of the container, and a recessed domed central panel extending upwardly and inwardly from the inner frustoconical surface to the axis of the container.

In order to assure adequate and uniform coating on the interior of the can at the bottom, the inner frustoconical surface may taper upwardly and inwardly at an angle in excess of 5 with respect to the axis of the can. Such an angle exposes the interior of the annular head to assure uniform and proper coating even when the frustoconical surface tapers inwardly and downwardly at an angle of less than 50 with respect to the axisof the can.

In order to provide the necessary pressure resistance without sacrificing stability, the central panel is recessed and domed to a point above the top of the outer frustoconical surface. In this connection, it has been found desirable to recess the edge of the domed central panel a distance above the supporting surface of the annular bead equal to at least 50 percent of the height of thev outer frustoconical surface. it has also been found desirable to utilize a doming radius which is no greater than twice the radius of the annular supporting surface.

BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT In the preferred embodiment of FIG. 1, a steel container. comprises a unitary body 12 including side walls 14 and an integral bottom 16. An end 18 is double seamed to a necked-in portion of the otherwise substantially cylindrical side walls 14.

In accordance with several important aspects of the invention, the. bottom 16 is provided with an easily coated, pressure resistant, and stable configuration. More particularly, the bottom 16 comprises a first and outer frustoconical surface 20 extending downwardly and continuously inwardly from the side walls 14,.an annular supporting head 22 extending from the outer frustoconical surface 20, a second or inner frustoconical surface 24 extending upwardly and continuously inwardly from the bead 22, and a recessed domed central panel 26 extending from the inner frustoconical surface 24 to the axis of the container 10.

lnorder to facilitate a more detailed discussion of the bottom configuration, reference will now be made to FIG. 2. One very important object of the invention is to allow a uniform and an adequate coating of a material; e.g., modified vinyl acetate or vinyl chloride polymer on the interior of a seamless container with a pair of individually electrically controlled, conventional spray nozzles 27. The. characteristic spraying pattern of the nozzles 27 has been depicted through the use of laterally extending arrows 28 directed toward the side walls 14 and the bottom 16. It has been found that the particular bottom configuration shown in FIG. 2 does provide a uniform and adequate coating of the bottom 16 when the conventional spray nozzle 27 is utilized.

One difficulty in coating the bottom 16 arises at the interior of the annular bead 22 with difficulties increasing-as the concavity of the bead 22 increases. To a certain extent, the concavity of the bead 22 is dictated by an angle A between the outer frustoconical surface '20 and the axis of the container 10. As the angle A increases, the concavity of the bead 22 decreases thereby decreasing the coating difficulties. However, an increase in the angle A results in narrower base of support or smaller radius of support R provided by the annular head 22. The smaller radius of support R renders the container 10 less stable or more likely to tip over. On the other hand, the smaller angle A not only increases the concavity of the annular bead 22 but also results in an angle A which is incompatible with the drawing angle of steel, approximately 45, as well as precluding the nesting of cans where the upper portion of the side walls 14 are necked-in as shown in FIG. 1. For this reason, the angle A is limited to a range of 30 to 50 with 40 being preferred. With this range for the angle A, it has been found that the interior of the annular bead 22 defined in part by the angle A formed by the frustoconical surface 20 may be coated adequately and uniformly by providing a proper angle 13 between the inner frustoconical surface 24 and the axis of the container 10. In particular, it has been found that the angle B should lie in the range of 5 to 20.

Due to the wide base of support established by the radius R which may represent approximately percent of the radius R for the container 10 at the side walls 14, and is somewhat larger than the radius R at the edge of the central panel 26, substantial eversion problems do exist for internal pressures approaching or in excess of IOOPSI. In order to solve these eversion problems, the central panel 26 is domed with a particular radius of curvature R and recessed to a particular height H,. With a radius of curvature R which is no more than twice the radius R,, (preferably a little larger than the container radius R and a recess height H at the edge of the panel 26 which is greater than 50 percent of the overall height I-I of the frustoconical surface 20, the central panel 26 extends above the uppermost portion of the frustoconical surface 20. With the central panel 26 domed and recessed in this manner, pressure resistance is provided .to prevent eversion. It is also believed. that central panel 26 facilitates the uniform and adequate coating of the annular bead 22.

Illustrative dimensions for the container of FIGS. 1 and 2 are as follows where the thickness of the central panel is 0.0118 inches.

H .203 inches H .340 H, .486 R .923 R 1.030 R,- R 1.575

In FIG. 3, a prior art aluminum seamless container is shown. As mentioned previously, the coating of the bottom of an aluminum container is not of particular concern in contrast with the situation for a steel container. In this connection, it will be noted that the angle B between the inner surface 44 of the bottom and the axis of the aluminum container is approximately 0 with the angle A between an outer surface 40 and the axis of the container being 375. From an eversion standpoint, it should be noted that the domed and recessed central panel 46 does not extend above the top of the outer surface 40 which has an overall height l-I nor is the recess height H at the edge of the central panel 46 equalto at least 50 percent of the height H,,. The radius of curvature R for the domed central panel 46 is more than double the radius R,, and nearly double the radius R Finally, due to the 0 angle B, the radius of the central panel edge R is substantially equal to the radius It is clear from the foregoing that the described prior art configuration for aluminum containers is quite different from the configuration of the steel containers of FIGS. 1 and 2 resulting in substantial differences in coating and eversion characteristics. In order to appreciate the differences in eversion characteristics for steel containers having different configurations at the bottom following tabulations may be referred to:

Container I LA 15 LB 15 H,, .197 inches H .178 H, .545 R 1.073 R,, 1.190 inches R 1.300 R 1.750

Eversion Pressures for Different Bottom Thicknesses Thicknessflnches) Pressure(PSI) .01 18 98 .01 12 96 .0107 84 Container 11 LA 15 48 15 H .197 inches H .178 H, .483 R,- 1.073 R, 1.190 R 1.300 R 2.038

Eversion Pressures for Different Bottom Thickness Thicknessflnches) Pressure(PSl) .01 17 96 .01 16 96 .01 15 96 .0105 86 .01 84 Container 111 LA 48 15 H,, .197 inches H .178 H, .432 R,- 1.073 R,, 1.190 R 1.300 R 2.528

Eversion Pressures for Different Bottom Thickness Thickness( Inches) Pressure(PSl) Container lV LA 40 48 15 H .192 inches H .328 H, .542 R,- .929 R,, 1.030 R l.300 R,- 1.3375

6 Eversion Pressures for Difierent Bottom Thickness Thickness( Inches) Pressure( PSI Container V 4. A 40 4 B 15 11,, .203 H .340 H, .435 R .923 R, 1030 R. 1.300 R 1.575

Eversion Pressures for Different Bottom' thicknesses Thicknessflnches) Pressure(PSI) .0121 132 .01 19 124 .Ol 18 121 .01 17 124 .01 15 .01 13 l 18 .01 10 103 .0108 108 It may be seen that a greater resistance to eversion is established for larger angles of A for a given thickness. It will also be seen that greater resistance to eversion is established where the domed central panel is further recessed and where the radius of curvature R is small although a radius of curvature which is too small has a lesser resistance.

The seamless container of the invention as disclosed in FIGS. 1 and 2 may be formed by utilizing a plurality of steps depicted by FIGS. 4 a-e. The process begins with a 107 lb. gauge (0.0118 inch) steel'blank 50 as shown in FIG. 4a. The blank 50 is then drawn to form a cup 52, redrawn to form a cup 54 of lesser diameter, and wall ironed to form an elongated cup 56 as shown in FIGS. 4 b-d respectively. Note the drawing angle of 45 shown in FIG. 4b and the redrawing and wall ironing angle of 40 shown in FIGS. 4 c and d. This 40 wall ironing angle is retained during the doming operating of FIG. 4e and becomes the angle of the outer frustoconical surface 20. A punch means 58 and doming die means 60 which is appropriately shaped to achieve the bottom configuration 16 shown in FIG. 2 is also depicted in FIG. 4c. The shapes of the punch 58 and the die 60 provide the configuration for the bottom 16 including the frustoconical surface 20, the annular bead 22, the frustoconical surface 24, and the central panel 26. The side walls 14 of the unfinished container 10 may then be trimmed, necked-in, and flanged prior to double seaming at the end 18 to the upper extremity of the side walls 14. The resulting configuration of the bottom 16 does permit the bead 22 to rest upon the central panel portion of another can end 18 of a like container where the side walls have been necked-in as shown in FIG. 1. For further details of the various steps depicted by FIGS. 4 a-e, reference may be made to application, Ser. No. 62,791, filed Aug. 1 l, 1970,

Although a particular drawing and wall ironing apparatus and method of operation have been described, various changes and modifications can be made without departing from the spirit of the invention or the scope of the appended claims.

What is claimed:

1. An internal pressure resistant steel container comprising a unitary body having seamless substantially cylindrical side walls and a bottom integrally formed with the side walls at the lower extremity thereof and further comprising an end double seamed to the upper extremity of the side walls, said bottom comprising an outer substantially frustoconical surface extending downwardly and inwardly from said side walls toward the axis of said container at an angle in the range of 30 to 50, a bead integrally connected with and extending downwardly from said outer frustoconical surface and providing an annular supporting surface for said can, said annular surface having a radius less than 90 percent of the container radius at said side walls, an inner substantially frustoconical surface integrally connected with and extending upwardly and inwardly from said bead toward theaxis of said container at an angle in the range of 5 to the height of said inner frustoconical.

surface being less than but more than half the height of said outer frustoconical surface, and a downwardly concave central panel extending upwardly and inwardly from the peripheral edge of said central panel, said peripheral edge being integrally connected to the upper edge of said. inner frustoconical surface, said central panel extending substantially above the uppermost portion of said outer frustoconical surface at the axis of said container.

2. The container of claim 1 wherein the radiusof cur-. vature of said downwardly concaved central panel is no greater than twice said radius of said annular supporting surface.

3. The container of claim 2 wherein said upper extremity of said side walls is necked-in such that the maximum outside diameter of said double seamed end is less than the outside diameter of said cylindrical side walls, said angle of said outer frustoconical surface with respect to the axis of said container permitting said annular supporting surface to rest upon and be supported by the central panel portion of said double seamed end.

4. A pressure resistant steel container capable of withstanding a substantial internal pressure without eversion comprising a unitary body having seamless substantially cylindrical side walls and a bottom integrally formed with the side walls at the lower extremity thereof and an end double seamed to a necked-in portion of the side walls at the upper extremity, the maximum outside diameter of the end being substantially less than the diameter of said cylindrical side walls beneath said end, said bottom comprising van outer surface extending downwardly and inwardly from said side walls toward the axis of said container, a bead integrally connected with and extending downwardly from said outer surface providing an annular supporting surface for said can, said outer surface extending sufficiently inwardly to permit said annular supporting surface to rest upon the substantially planar surface of the central panel of an end on a like container, an inner surface integrally connected with said head and extending upwardly and inwardly from said annular bead toward the axis of said container, and a downwardly concave central panel integrally connected with said inner surface and extending upwardly and inwardly from said inner surface to the axis of said container, said central panel extending above the uppermost portion of said outer surface.

5. The container of claim 4 wherein said outer surface is subs ant'all fr st conical formin an an le in the range 0 30 to 50 w?th respect to th e axis of said container.

6. The container of claim 4 wherein said inner sur-' face is a substantially frustoconical surface forming an mg?" CW5 um'm s'm'm'gs PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,693 828 Dated Septemk e; 26 19 72 1nvcntor(s) Raymond H.P. Kn'eusel and Vinson S. Potts It is certified that error appears in the above-identified patent: and that said Letters Patent are hereby corrected as shown below:

' Title vpage, line 5, "Crown Corp &,Seal Company, Inc." should read -Crown Cork & Seal Company, Inc.--

Col. 4 line 57 "R5 should read R 1.3od"--.

Col. 6, line '67, delete "steel".

-Col. 6, line 68, afterf'unitary" insertsteel-.

Col. 8, line 2, delete steel i Col. 8, line 4, after'fiqnitary" insert -steel--.

Signed and sealed this 13th day of March 1973..-

(SEAL) I a Attest:

EDWARD(M.FLET(IHER,JR.' RoisERT GOTTSCHALK Attestlng Offlcer Commissioner of Patents 

1. An internal pressure resistant steel container comprising a unitary body having seamless substantially cylindrical side walls and a bottom integrally formed with the side walls at the lower extremity thereof and further comprising an end double seamed to the upper extremity of the side walls, said bottom comprising an outer substantially frustoconical surface extending downwardly and inwardly from said side walls toward the axis of said container at an angle in the range of 30* to 50*, a bead integrally connected with and extending downwardly from said outer frustoconical surface and providing an annular supporting surface for said can, said annular surface having a radius less than 90 percent of the container radius at said side walls, an inner substantially frustoconical surface integrally connected with and extending upwardly and inwardly from said bead toward the axis of said container at an angle in the range of 5* to 20*, the height of said inner frustoconical surface being less than but more than half the height of said outer frustoconical surface, and a downwardly concave central panel extending upwardly and inwardly from the peripheral edge of said central panel, said peripheral edge being integrally connected to the upper edge of said inner frustoconical surface, said central panel extending substantially above the uppermost portion of said outer frustoconical surface at the axis of said container.
 2. The container of claim 1 wherein the radius of curvature of said downwardly concaved central panel is no greater than twice said radius of said annular supporting surface.
 3. The container of claim 2 wherein said upper extremity of said side walls is necked-in such that the maximum outside diameter of said double seamed end is less than the outside diameter of said cylindrical side walls, said angle of said outer frustoconical surface with respect to the axis of said container permitting said annular supporting surface to rest upon and be supported by the central panel portion of said double seamed end.
 4. A pressure resistant steel container capable of withstanding a substantial internal pressure without eversion comprising a unitary body having seamless substantially cylindrical side walls and a bottom integrally formed with the side walls at the lower extremity thereof and an end double seamed to a necked-in portion of the side walls at the upper extremity, the maximum outside diameter of the end being substantially less than the diameter of said cylindrical side walls beneath said end, said bottom comprising an outer surface extending downwardly and inwardly from said side walls toward the axis of saiD container, a bead integrally connected with and extending downwardly from said outer surface providing an annular supporting surface for said can, said outer surface extending sufficiently inwardly to permit said annular supporting surface to rest upon the substantially planar surface of the central panel of an end on a like container, an inner surface integrally connected with said bead and extending upwardly and inwardly from said annular bead toward the axis of said container, and a downwardly concave central panel integrally connected with said inner surface and extending upwardly and inwardly from said inner surface to the axis of said container, said central panel extending above the uppermost portion of said outer surface.
 5. The container of claim 4 wherein said outer surface is substantially frustoconical forming an angle in the range of 30* to 50* with respect to the axis of said container.
 6. The container of claim 4 wherein said inner surface is a substantially frustoconical surface forming an angle in the range of 10* to 20* with respect to the axis of said container. 